PHYSICS - CH 2

What is distance?

Depends on the path that is covered by an object, it is a scalar quantity

A measure of how far an object has travelled

What is displacement?

The shortest distance from the start point to the end point

On a coordinate plane, which directions are taken as positive?

Right (East) and Up (North) are considered to be positive on a coordinate plane

On a coordinate plane, which directions are taken as negative?

Left (West) and Down (South) are considered to be negative on a coordinate plane.

What is average speed?

Speed is the total distance travelled by the object in a particular time interval

What formula is used to calculate average speed?

Average Speed (m/s) = Total Distance (m) / Time taken (s)

S = D/t

What is average velocity?

Average velocity is the change in displacement relative to time.

What formula is used to calculate average velocity?

Average Velocity (m/s) = Displacement (m) / Time taken (s)

V = ∆d/ ∆t

What does the slope of a position-time graph give you?

∆Position / ∆Time = velocity

What does slope of the absolute value of a position-time function give you and why?

Speed, as it is a scalar quantity and is always positive.

What happens as the slope of the position-time graph increases?

Motion with more average velocity

Average Velocity is ____ when the line goes ____.

Positive, Up

Negative, Down

A motorcycle moves with a constant speed of 6m/s. What is the distance covered in 5 seconds.

Distance = S x t = 6 x 5 = 30m

What is average acceleration? What is the unit for acceleration?

Average acceleration is the change in velocity divided by the time. It is measured in m/s^2

What formula is used to calculate average acceleration?

Average Acceleration = ∆Velocity (m/s) / ∆ time (s)

What does the slope of the velocity time function give you?

Average acceleration

Acceleration is ___ as velocity ____ with time

Positive, Increases

Negative, Decreases

What does the area under a velocity-time graph represent?

∆Position/∆Time x ∆Time = ∆Position = Displacement

What is instantaneous acceleration?

The acceleration of an object at a given instant in time

What can you infer about a graph where the slope of a velocity-time graph is linear?

The instantaneous acceleration = The average acceleration

What can you infer about an object that moves with constant velocity/speed?

It has no acceleration

Is acceleration a scalar or a vector quantity?

Vector Quantity

Calculate the acceleration of an object with a change in average speed of 40m/s in 2 seconds.

∆Speed / ∆Time = Acceleration

40 m/s / 2 s = 20m/s^2

A racecar accelerates from 4 m/s to 24 m/s in 4 seconds, find it's acceleration in m/s^2 ?

Acceleration = ∆Velocity / ∆Time = 24-4 / 4 = 20/4 = 5m/s^2

What is a motion diagram? How can they be represented?

A series of images showing the positions of a moving object at equal time intervals. They can be represented as dots

On a motion diagram, what does an increase in the space between each dot represent?

Acceleration

What are the three equations of motion with constant acceleration

v = v0 + at

x = x0 + v0t + 1/2at^2

v^2 = (v0)^2 + 2a (x-x0)

What constant(s) are used for acceleration due to gravity?

g = 9.8 or 10

What is the difference between horizontal motion with constant acceleration and vertical motion with constant acceleration (Free Fall) ?

Acceleration is replaced with g, and g is always = -9.8 m/s^2

How does the speed of an object change as it goes up/down?

The speed of an object decreases as it goes up, and it increases as it goes down

What can be inferred about the velocity of an object at its peak during free fall?

The velocity = 0

Note: Acceleration doesn't become 0, even if velocity = 0.

Does mass have an effect on free falling motion?

No, it is not included in any of the constant acceleration formulas.

What can be said about the time going up and the time going down for an object in free fall when thrown upwards?

Time going up = Time going down

What are contact forces?

Forces in which two or more objects or bodies touch or contact each other directly

What are examples of contact forces?

Friction, elastic forces, air resistance, push and pull, normal force

What are field forces (non-contact forces) ?

A force that affects objects without contact between them

What are examples of non-contact forces?

Magnetic Force, Electric Force, Gravity

What is newton's first law of motion?

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

What is newton's second law of motion?

a net force acting on an object causes the object to accelerate in the direction of the force

∑F = ma

What is inertia?

Inertia is the resistance of the object to any change in its motion statement. This includes changes in the object's speed or direction.

What is weight? What unit is used to measure it?

Weight is the force of gravity acting on an object, measured in newtons.

W = mg

What is Newton's third law?

When two bodies interact, the applied forces to one another are equal and magnitude and opposite direction, also known as the "equal action and reaction" law

What makes mass different from weight?

Mass is equal everywhere on Earth, while weight depends on the gravitational acceleration of the location

The resultant vector of two vectors, A & B, acting in the same direction can be written as?

R = A + B

The resultant vector of two vectors, A & B, acting in the opposite directions can be written as?

R = A - B, where A > B

The resultant of two perpendicular vectors can be given as?

R = √(A^2 + B^2)

The resultant of two vectors with an angle θ can be given as?

R = √(A^2 + B^2 - 2ABcosθ)

What is normal force?

Normal Force is a contact force, in which a surface vertically affects an object.

What can be said about normal force on a horizontal surface?

Normal force on a horizontal surface = mg

What is friction force?

It is a force that prevents the moving of objects or stops them

What are the types of friction?

static friction (⨍s) and kinetic friction (⨍k)

How is kinetic friction (⨍k) calculated?

⨍k = coefficient of kinetic friction x normal force

How is static friction (⨍s) calculated?

⨍s (max) = coefficient of static friction x normal force

static >/< kinetic friction?

Static friction > Kinetic Friction

What unit is used to measure coefficients of friction?

They are unitless

If an object isn't touching the ground or any surface, what is its normal force?

0

How do you find the Fx component (horizontal component) when given a vector?

Fx = F cos θ

How do you find the Fy component (vertical component) when given a vector?

Fy = F sin θ

How is Normal Force calculated on an incline?

F (normal) = mg cos θ

What can be said about the normal force for an object on an incline?

The normal force is always perpendicular to the surface.

What can be said about the velocity in the horizontal component during projectile motion?

It is constant, horizontal acceleration = 0

What can be said about the velocity in the vertical component during projectile motion?

It changes because of acceleration due to gravity

What can be said about velocity of an object at its highest point during projectile motion?

Vy = 0,

Vx = Vix (initial horizontal velocity)

The gravitational acceleration is ____ when an object goes ____ in projectile motion (vertical motion)

Negative, up

Positive, down

What condition has to be met in order for an object to have symmetry in its speed?

The object has to land on the same level it was launched from

What is the formula used to calculate time of maximum height for a projectile?

t = v0 sin θ / g

Why would an object fired horizontally and an object dropped from rest both land at the same time?

Both objects have an initial vertical velocity of 0

How do you find the Fx component (horizontal component) when given a vector?

Fx = F cos θ

How do you find the Fx component when given a vector?

Fx = F cos θ

How do you find the Fx component when given a vector?

What is circular motion?

The motion of an object with constant speed in a uniform circular path with constant radius

What is centripetal acceleration?

The acceleration of an object that moves in uniform circular motion and

What can be said about the direction of the centripetal acceleration of an object?

Its direction is pointed toward the center of the circular path

What is centripetal force?

It is the resultant force that causes the centripetal acceleration and is directed to the center of the circular path.

How can you calculate centripetal acceleration?

α = v^2/r

How can you calculate centripetal force?

Fc = mα = mv^2/r

How else can centripetal acceleration be calculated?

α = 4π^2r/T^2

How can tangential velocity be calculated in a context of circular motion?

v = 2πr / T

How can you calculate circumference of a circle?

Circumference = 2πr

What is T? How can you calculate it?

The time it takes an object to cover one revolution

T = 2πr / v

What would happen to an object in circular motion around the earth if the force of gravity stopped? Why?

The object would continue in the same direction of its tangential velocity because gravity causes centripetal acceleration

What is Kepler's first law?

All planets move about the Sun in elliptical orbits, having the Sun as one of the foci

What is Kepler's second law?

A radius vector joining any planet to the sun sweeps out equal areas in equal lengths of time

What is Kepler's third law?

The squares of the sidereal periods (of revolution) of the planets are directly proportional to the cubes of their mean distances from the sun

What is Kepler's third law? (Formula)

(T𝚨/T𝘽)^2 = (r𝚨/r𝘽)^3

What happens to the speed of the earth as it gets closer to the sun?

It increases

What is angular motion?

Angular motion is the movement of an object around a fixed point or axis.

The complete rotation of a body around itself makes an angle = 2 π radians

What us angular displacement? (Δθ)

It is the shortest angle between an object's initial and final positions during circular motion around a fixed point; it is considered a vector quantity.

What is the number of cycles in angular motion?

The number of cycles measures how many revolutions an object has completed around a circle when rotated about itself

How can the number of cycles be calculated?

N = θ / 2π

What is angular velocity? ω (omega)

It is the rate of change of angular position of a rotating body.

How can you calculate angular velocity? (2 formulas)

ω = θ / Δt OR ω = v / r

What is angular acceleration?

Angular acceleration is the change in angular velocity divided by change in time

How can you calculate angular acceleration? (2 formulas)

𝛼 = Δω / Δt OR 𝛼 = a / r

How can you calculate centripetal acceleration using angular velocity and radius?

α(c) = ω^2r

How can you calculate angular displacement, velocity, and acceleration?

displacement: θ = d/r

velocity: ω = v / r

acceleration: α = a / r

How can you calculate transitional displacement, velocity, and acceleration?

displacement: d = rθ

velocity: v = rω

acceleration: a = rα

How can you calculate the force of gravity?

Fg = G Mm / r^2 = mg

How can you calculate the acceleration due to gravity of a planet?

g = G x Mass of planet/r^2

The force of gravity between two planets is directly correlated to their _____ and inversely related to the ____ between their centers

masses, distance/radius